Amazon's page says this - probably copy from the back.
The only links between the far-flung space colonies were the Medical Services spaceships. When these lonely travelers paid a call, they were always given a royal welcome. So why did the landing grid on Marix III try to destroy Med Serviceman Calhoun's ship?
I don't know. I've just no idea. Let's find another review . . . ah.
Med Serviceman Calhoun has a routine planetary medical review turn into a battle against a man-made plague and those who created it. Calhoun finds himself fighting a plot not only to steal a planet, but possibly an entire galaxy.
Not enough to steal a planet. No, try for an entire galaxy, because that's both plausible and doable.